diff --git a/TODO b/TODO
index 1e859984..ae4eec10 100644
--- a/TODO
+++ b/TODO
@@ -13,6 +13,8 @@ Version 1.5.0:
 * Distributed clocks:
     - Delay calculation.
     - Synchronize the reference clock to the master clock.
+    - Reference clock zero.
+    - Configuration must exist, config state machine.
 * Read alias from register 0x0012 instead of SII.
 * Finish library implementation.
 * Re-work EoE code.